Nowadays, turbine components are often made from materials with a directional microstructure. In this context, materials with a directional microstructure are to be understood as meaning in particular single-crystal materials and materials which have a grain structure wherein the grains extend in a common preferential direction. By way of example, the grains may have a larger dimension in a certain preferential direction than in the other directions. Components with a grain structure of this type are also known as directionally solidified components.
Highly stressed components, such as for example turbine blades or vanes, are subject to high thermal and mechanical stresses in operation, which can lead to material fatigue and as a result to cracks. Since it is relatively expensive to produce components from base materials which have a directional microstructure, the general aim is for components of this type to be repaired after damage has occurred. This restores the functionality and allows the component to be used for a further maintenance period.